## Friday, January 13, 2012

### Polar

A coordinate (x,y) in xy-plane can be written in polar form $\left ( r,\theta \right )$, where r is the directed distance from (0,0) to (x, y), and $\inline \theta$ is the directed angle formed by the vector <x, y> from the positive side of x-axis:

$r=\sqrt{x^2+y^2}$

$\theta =\tan^{-1}\left ( \frac{y}{x} \right )$

There are some interesting graphs can be obtained through polar equations, such as
etc.

Click on the content alongside to look at the shapes mentioned above.